In the wee hours of this morning, the JVM has for the first time processed a full bootstrap cycle for invokedynamic instructions, linking the constant pool entries, creating the reified call site object, finding and calling the per-class bootstrap method, linking the reified call site to a method handle, and then calling the linked call site 999 more times through the method handle, at full speed. The method names mentioned by the caller and the callee were different, though the signatures were the same. The linkage was done by random, hand-written Java code inside the bootstrap method.

The 'invokedynamic' instruction is one of many efforts planned as part of the multi-language virtual machine dubbed the 'Da Vinci Machine'. All of the planned feature enhancements in Da Vinci are described on the sub-project section of the MLVM site. Dynamic invocation is also part of JSR-292, which has been previously discussed on InfoQ, and is an adaptation of some of the experimental Da Vinci work into the core Java VM. This announcement by John Rose is the first time that 'invokedynamic' has run on the OpenJDK hotspot virtual machine.

There is still a long road left for dynamic invocation, however. Of course, dynamic languages (such as JRuby and Groovy) must adapt to utilize the new instruction. Rose also details that there is still work to be done in the core implementation:

As for the JVM code, it only works on x86/32; the next step is to move the assembler code into the right files, and finish the support for x86/64 and SPARC.